1. Field of the Invention
This invention relates to an auxiliary mechanism mounting structure for an engine for mounting an auxiliary mechanism on the engine.
2. Description of the Prior Art
In a power plant for a vehicle which includes an engine, a transmission and the like, power plant vibration is produced. Connections in the power plant are generally increased in rigidity so that the power plant vibration does not resonate in the practical engine speed range. However, in a vehicle in which a differential is provided near the transmission, for instance, a four-wheel drive vehicle, the resonant frequency shifts to a relatively low engine speed range within the practical engine speed range due to difference in weight distribution and large vibration is produced, which gives rise to various problems. For example, noise in the passenger room increases. Accordingly, various measures such as increasing the rigidity of the power plant and improvement of the power plant mounting portion have been taken in order to suppress the power plant vibration.
Further, since the auxiliary mechanisms for the engine, e.g., a compressor for an air conditioner, vibrate in response to the vibration of the engine, it has been proposed to provide the auxiliary mechanism with a dynamic damper which damps the resonation of the auxiliary mechanism. (See Japanese Unexamined Utility Model Publication No. 62(1987)-190831)
However, increase in the rigidity of the power plant involves increase in weight and/or cost, and improvement of the power plant mounting portion encounters a difficulty in setting the properties of the mounting portion so that the power plant vibration is suppressed. Further, providing the auxiliary mechanism with the dynamic damper also involves increase in weight and/or cost.